Design and installation of fixed foam fire extinguishing system

1. DESIGN AND INSTALLATION OF FIXED FOAM FIRE EXTINGUISHING SYSTEM
Foam for fire fighting purposes is essentially an aggregate of gas filled bubbles, formed from an aqueous solution
of a suitable foaming agent or concentrate. The gas used is normally air, but in certain applications, inert gases
have been used.
Foam is produced by mixing a foam concentrate with water to the appropriate concentration, and aerating and
agitating the solution to form the bubble structure. The ratio of the volume of the made foam to that of the
solution from which it is made is defined as the expansion. Other important foam properties are also defined. One
of these is the critical shear stress, a measure of the stiffness of the foam and hence an inverse measure of its
ability to flow readily over a fuel surface and around solid obstructions. Another is its drainage time, a measure of
the stability of the foam, which relates both to its stiffness and ability to resist destruction by the radiant heat of
the flames.
Foams are arbitrarily subdivided into three ranges of expansion, these ranges corresponding broadly to certain
types of usage which are described below.
The three ranges are approximately:
(LX) Low expansion foam—expansion up to 20
(MX) Medium expansion foam—expansion 20 to 200
(HX) High expansion foam—expansion 200 to 1000
Low expansion foams are generally used for the extinction of fires in flammable liquids by the formation of a
blanket over the surface of the liquid, thereby reducing the rate of release of flammable vapours to the combustion
zone below that which is necessary to maintain burning. The fires may include pool or spill fires, or fires in tanks
and similar containers.
Low expansion foams may be applied directly to the surface of the burning liquid (surface application) or may be
applied in the case of tank fires, below the surface so that they float to the surface under their own buoyancy
(subsurface application). Low expansion foams may also be applied by a semi sub-surface method. For gasoline
and light crude oils, AFFF should be used.
Low expansion foams may be used for the suppression of vapour emission from spillages of flammable liquids.
They can also be used to protect other risks from radiant heating, providing the foam layer is regularly
replenished, and they can have a limited usefulness in the extinction of surface fires in solid combustibles.
Limitations on the use of low expansion foams are as follows:
a. They are not generally suitable for the extinction of running fuel fires, that is, fuel running from a leaking
container or from damaged pipework or pipe joints.
b. Since all fire fighting foams are made from aqueous solutions, they may be 1ineffective or dangerous to
use on flammable liquids with temperatures much in excess of 100°C, particularly where these fires are in
liquids of considerable depth of in-tank fires. Drainage of the water from the foam may result in the
formation of steam which can cause frothing or slop-over of the burning liquid unless due precautions are
taken to avoid this. Foams may, however, sometimes be used to cool the surface layers of a flammable
liquid below the fire point, provided the temperature is not greatly in excess of 100°C.
c. Most aqueous foams are not suitable for use on water-miscible flammable liquids, which can cause rapid
breakdown of the foam by extraction of the water from the bubble walls. For these flammable liquids,
specially stabilized foam concentrates are used.

2. d. Foams are not suitable for use on fires involving gases, or liquefiable gases with boiling points below 0°C,
or cryogenic liquids.
e. Because foams are made from aqueous solutions they may be dangerous to use on materials which react
violently with water, such as metallic sodium or potassium. They can, however, sometimes be used with
care on magnesium fires to help restrict burning by cooling the residual metal.
f. Low expansion foam is a good conductor and should not be used on energized electrical equipment.
g. Certain wetting agents and some extinguishing powders may be incompatible with foams, causing a rapid
breakdown of the latter. Only agents which are substantially compatible with these foams should be used
in conjunction with them, in such cases AFFF should only be used.
h. Only certain types of foam concentrates are suitable for storage in the diluted or pre-mixed condition.
AFFF can be kept in premixed condition up to 1 year. Protein base foams are unsuitable for keeping in
premixed condition.
i. Simultaneous use of water jets or sprays may adversely affect a foam blanket, and their use should not be
envisaged in conjunction with these foams unless it has been shown that this will not occur.
The following types of low expansion foam concentrates:
a. Protein Foam Concentrates (P)
These are liquids containing hydrolized protein materials with the addition of certain salts to improve
stability and storage properties. Protein foam concentrates are usually manufactured for use in
concentration of 3 percent and 6 percent. Foams produced from these concentrates are relatively stable,
have low rates of liquid draining, are relatively stiff and have good heat resistance.
Protein foams are not suitable for use in sub-surface systems in fuel storage tanks but may be, however,
applied by a semi-surface method.
b. Fluoroprotein Foam Concentrates
These are made from protein-based concentrates by the addition of fluorinated and other types of surface
active agents. An effect of adding these surfactants is to give a foam of lower shear stress whilst retaining
satisfactory heat resistance. This results in the foam flowing more quickly than protein foams across the
fuel surface and around any obstructions giving faster control and extinction. The improved flow
properties and the higher surface activity gives the foam self sealing properties, that is, if the foam blanket
is broken the foam will flow readily to reform a complete blanket. A further advantage of fluoroprotein
foams over protein foams is that they are far less vulnerable to contamination by hydrocarbon fuels, and
are suitable for use in sub-surface systems. These foam concentrates are usually available for use in 6
percent concentrations. Fluoroprotein foams exhibit good sealing against hot metal edges.
c. Aqueous Film Forming Foam Concentrates (AFFF)
These foam concentrates, which may also be referred to as fluorochemical foam concentrates, are based
on fluorinated surface active materials in combination with other surface active agents and stabilizers. The
foams produced are more fluid than fluoroprotein foams, having low critical shear stress values and also
short drainage times. They give very quick control and extinction, but the fast drainage means that they do
not have high heat resistance and they may have less burnback resistance than protein and fluoroprotein
foams. A feature of these foams is that the solution draining out of the foam is capable of forming a
floating film on the surface of some liquid fuels. This can give protection against re-ignition and give re-
sealing properties should the foam blanket be broken. These concentrates are usually available for use in 6
percent concentrations. They may be used for sub-surface systems.
LOW EXPANSION FOAM SYSTEMS FOR SURFACE
APPLICATION

3. Systems producing foams with expansions up to 20, in which the foam is applied directly to the surface of the
burning fuel by means of fixed nozzles, sprayers, pourers or monitors. The usual expansion range for such
systems is between 6 and 12.
Rate of Application of Foam Solution
Requirement
The system should provide a minimum application rate of foam solution per unit area, when tested in accordance
with the method of test given .
Method of Test
Apparatus
Install a pressure gauge adjacent to the discharge point in the hydraulically most remote location, with respect to
the main foam solution supply line to the system. It is essential that the K factor of each nozzle is known
Procedure
Discharge the system and record the steady state discharge pressure (P) at each of the nozzles. Visually examine
all discharge points to see that they are operating satisfactorily.
NOTE—Water may be used instead of foam solution to avoid the need for extensive cleaning of the system after
test.
The discharge point may be a nozzle, sprayer, pourer or monitor, but for simplicity will be referred to here as a
‘nozzle’.
Calculation
Q = K/P
where
Q is the foam solution flow rate—l/min,
K is the nozzle discharge coefficient, and
P is the steady state nozzle pressure-bar.
Divide Q by the area a (in square metres) designed to be covered by that nozzle, that is, Q/a. Compare the value
of Q/a with the minimum acceptable value.
Foam Distribution
A full-scale foam discharge test should be conducted to ensure that the system is capable, in accordance with the
design requirements, of producing and maintaining an even foam blanket over the surfaces to be protected.
Particular attention should be paid to the possible effects of wind, and of obstructions such as pipework, pumps,
motors, vessels, etc, so as to ensure that there are no areas of reduced foam coverage where fuel can burn
unhindered.

4. LOW EXPANSION FOAM SYSTEMS FOR SUB-SURFACE
APPLICATION
General
The system should provide a minimum application rate of foam solution per unit area, when tested in accordance
with the method application rate.
Method of Test
Apparatus
The foam supply and test lines and their associated valve arrangements and if the system has
more than one injection point per generator then the foam should be sampled on the line leading to the most
remote point. It is essential that the foam generator discharged should be known.
Calculation
Using the formula Q = K/P
where Q is the foam solution flow rate—l/min
and P is steady state inlet pressure-bar
Divide Q by the area (in square metres) protected by the injection point under test.
Foam Distribution
A check should be made to ensure that the foam injection points are hydraulically balanced.
BASIC TYPES OF FOAM SYSTEM
General
A foam system consists of an adequate water supply that can be pressurized, a supply of foam liquid concentrate,
a device to proportion correctly the water and foam concentrate and pipework or hose connected to equipment
designed to produce and to distribute foam over the risk.
Self-contained systems are those in which all components including water and foam concentrate are contained
within the system. Such system often have water and foam concentrate stored as a premix solution in a tank
which is pressurized by compressed gas when operated or
the foam concentrate can be stored and pressurized separately.
There are three basic types of systems and each may be used inside or outside buildings:
a. Installed, fixed or semi-fixed;
b. Portable; and

5. c. Mobile.
Installed Systems
Fixed:
This type has permanent steel pipework connected from the water supply via the fire water pump (if fitted) and
foam liquid proportioning device to the foam maker(s) which protect the hazard.
Semi-Fixed :
Permanent steel pipework is employed from an area adjacent to the risk, from which it is considered safe for
personnel to conduct fire fighting operations, to the foam maker(s) which protect the hazard. This pipework may
include the proportioning device, and has provisions for water supply hoses to be connected. The water supply is
usually pumped and foam concentrates provided by mobile fire appliances.
Portable:
This includes foam-producing units that can be carried by one or more men and connected via fire hose to a
pressurized water or premixed solution, supply, so as to produce foam jets, or sprays that can be applied to the
risk.
Mobile:
This includes foam-producing units mounted on wheels, and which may be self-propelled, towed by a vehicle or
pushed by hand. These units may be connected to a suitable water supply or may utilize a premixed foam
solutions. They can produce foam jets or sprays to cover the risk.
FOAM SYSTEM DESIGN
General
The system should be designed to suit the particular hazard and the following points should be considered:
a. Full details of the flammable liquid, its storage, handling and location need to be known before any foam
system is considered.
b. The most suitable foam-making concentrate (P, FP, AFFF) in the appropriate concentration.
c. The most suitable solution application rate.
d. Most suitable equipment for making and delivering foam.
NOTE—The selection may depend upon the available water pressure.
e. System operating time.
f. Quantity of foam concentrate required for extinction.
g. Most suitable proportioning method(s).
h. Pipework sizes and pressure losses.
i. Water supply requirements, quantity, quality and pressure so that suitable pumps may be selected.
j. System operation and any fire or gas detection equipment.
k. Any special considerations such as the use of electrical equipment in areas where flammable vapours may
be present.
l. Reserve foam concentrate supply.
m. Drainage and bunds.

6. Automatic Operation
In conditions where the onset of a fire may lead to a rapid escalation, the use of fixed foam systems designed for
automatic operation should be considered.
This will apply particularly to a risk situated in a building where any heat generated by fire cannot disperse as
readily as in a similar outdoor risk. It is therefore desirable that indoor fixed foam systems be designed for
automatic operation, supplemented by auxiliary manual operation.
WATER SUPPLIES, PUMPS AND DRAINAGE OF FOAM SYSTEM
Water OF FOAM SYSTEM
The quantity and flow rate of the water supply should be adequate to provide not only for the foam system but
also for any other fire-protective systems which may be used simultaneously with it, for the specified discharge
times, the details of which are given in IS 9668: 1980.
The water supply to foam systems may be hard or soft, fresh or salt, provided this has no adverse effects on foam
formation or foam stability. Particularly care should be taken to ensure adequate foam quality where the water
supply has been treated or otherwise contaminated.
Where solids of sufficient size to obstruct openings in the foam equipment may be present, strainers should be
provided.
The recommended water temperature for foam production is between 5°C and 38°C. Outside this temperature
range foam performance may be impaired. Precautions should be taken to prevent freezing taking into account the
combined effect of low temperature and high wind.
Water Pumps OF FOAM SYSTEM
Pumps providing a water supply to foam equipment need to be correctly sized and should be capable of operating
satisfactorily following long periods of inactivity. These should conform to relevant Standard. There should not
be any sluice or shut-off valve in the suction line. The pumps with valve arrangement should be tested at least
once per month.
The pressure supplied by the pump to the inlet of the foam system under required flow conditions should lie
within the range for which the system has been designed.
For a single pump installation, a suitable alternative water supply should be available. In general, multiple pump
arrangements are preferred to improve reliability. Emergency connection should be provided for connection of
fire hoses from trailer pump, etc.
Diesel engines are preferred to electric motors for driving pumps, unless stand by electric power can be relied
upon to be available in emergency.
The use of one diesel-driven and one electrically-driven pump of appropriate size is an acceptable arrangement.
Operation of the foam equipment, whether by automatic or manual means should cause the automatic operation of
the pump or pumps. In addition, arrangements for starting the pumps manually should be provided.
When pumps are electrically-driven, it is essential that the electrical supply be maintained to the pumping set. It is
therefore necessary to ensure that an alternative power supply is always available for the motor.

7. Switches on the power feed to the motor should be clearly labelled in white letters on a red background for
following, according to:
a. Fire equipment,
b. Pumps motor supply, and
c. Not to be switched off during fire emergency.
The lettering should be in upper and lower case with a minimum lower case letter height of 15 mm.
The electricity supply circuit should have an adequate short circuit protection.
Drainage of Bunds OF FOAM SYSTEM
Drains and interceptors of bunded areas should be of adequate capacity to carry the anticipated drainage of water
used in firefighting. The bund for an oil tank should be with a slope to the rain outlet not too close to the group of
product pipes.
FOAM CONCENTRATE SUPPLIED, PUMPS AND
PROPORTIONING SYSTEMS
Storage
Storage of foam concentrate or premix solution should be in an accessible location not exposed to the hazard they
protect. The material of construction of any housing should comply with the requirements of relevant Standard.
The tanks or containers should be made from materials suitable to store the concentrate for long periods without
risk of corrosion to the tanks or abnormal deterioration of the media—like glass fibre reinforced polyester.
Means should be provided to ensure that the concentrate or premix solution is kept within its design operating
temperature range. The storage temperature range should be as per relevant Standard.
Clear markings should be provided on storage vessels to identify the type of concentrate and its concentration in
solution. Many materials are not suitable for continuous immersion in foam concentrates because either the
material or the concentrate may be adversely affected. The protein foam should be tested after its shelf life.
Storage tanks should have capacities to accommodate the required quantities of foam concentrate or premix
solution with adequate ullage for thermal expansion. For tanks at atmospheric pressure this may be achieved by
means of a closed vertical riser or expansion dome. Where storage tanks require to be vented to atmosphere, the
air/liquid interface should be of the minimum practical area in order to minimize the possibility of interior tank
corrosion and sludge formation. A pressure vacuum vent valve may also be provided. Foam concentrate outlets
from tanks should be raised above the bottoms of the tanks to provide adequate sediment pockets. The capacities
of tank sediment pockets should be excluded in determining the effective capacity of the tank.
Pipework systems should be designed to be either charged or dry, to minimize situations when there may be an
air/liquid interface in a line or valve.
Tanks should be equipped with access for inspection and cleaning of interior tank surfaces, outlet connections and
testing lines; protected sight gauges or other contents measuring devices and filling, draining and sampling
connections. Pressure tanks should have a means of filling, a means to measure the contents available, a drain
valve and access for internal inspection and cleaning.
Reserve Supply for FOAM SYSTEM

8. It is essential that a reserve supply of the correct foam concentrate should be available to enable the system to be
put back into service
within 24 hours of operation. This supply may be stored in separate tanks, in drums or cans on the premises, or be
available from an outside source.
Adequate loading and transportation facilities should be assured at all times.
Other equipment which may be necessary to re-commission the system, such as bottles of nitrogen or carbon
dioxide for premix systems, should also be readily available.
Foam Concentrate Pumps OF FOAM SYSTEM
Pumps used for foam concentrates should be as reliable as fire pumps. They should be centrifugal type self-
priming, and driven by any suitable prime mover conforming to relevant Standard.
Materials of construction should be suitable for use with the type and grade of foam concentrate without risk of
corrosion, foaming or sticking. Special attention should be paid to the type of steel used. Stainless steel pumps are
preferred.
Pumps should have adequate capacities to meet the maximum system requirements. To ensure positive injection,
the discharge pressure rating at design discharge capacity should be sufficiently in excess of the maximum water
pressure likely under any condition at the point of injection of the concentrate.
Pumps should be provided with adequate means of pressure and flow relief from the discharge to the suction side
of the circuit to prevent excessive pressure and temperature.
Pumps which are arranged to stand dry should have means provided for flushing with clean water after use. They
should be provided with a drain down cock.
PIPEWORK DESIGN OF FOAM SYSTEM
Pipes, Connections and Valves
Wherever possible, valves and connections in the pipework to the risk should be located outside the hazard area.
Outside the Hazard Area
Pipes, connections and valves should be suitable for normal water use to the appropriate pressure specification.
Inside the Hazard Area
Pipe should be of steel or other alloy suitable for the pressure and temperature involved. Connections should be
welded, flanged for screwed with a taper thread. Where gaskets are required they should be fabricated from a
material which is non-combustible when tested in accordance with relevant Standard.
Foam concentrates have a lower surface tension than water, and they may cause internal pipe scale or sediment to
loosen, with the risk of blockage of sprayers, proportioning equipment, etc. Pipes and fittings should be carefully
cleaned before assembly, and any loose jointing material should be removed.
Pipe Size, Run and Supports of foam system

9. The pipework for each system should be hydraulically calculated and sized in order to ensure that pressure losses
are kept within design limits and that a reasonably uniform distribution is obtained. In this way, the cost will be
kept to a minimum while ensuring that each foam generator works most efficiently.
In locations where pipework may be exposed to fire or explosion, it should be coated to afford the best protection
against damage. This can be accomplished by running it close to major structural members. In such locations,
special consideration should be given to the spacing and type of pipe supports used. Use of cover pipe and where
required pipework may be encased in suitable resisting material.
Drainage of foam system
All dry piping should be arranged to drain and should have a minimum pitch towards the drain of 1 in 120.
Drain valves should be provided for premix or finished foam lines at low points in piping, whether below or
above ground.
Corrosion Protection of foam system
Internal Protection
Pipework should be of a type, or have a protective lining, which is compatible with the concentrate or premix
being used.
Dry foam system pipework may be galvanized providing that it is well washed thoroughly after use.
Alternatively, it may be protected internally by a suitable coating.
Wet foam pipework should not be galvanized as this may adversely affect the foam concentrate or premix
solution. Corrosion resistant material such as certain plastics or stainless steel may be used, or the pipework may
be protected with a suitable coating. Unlined steel or cast-iron pipework may not be suitable for wet use unless
flushed periodically.
External Protection
System pipework should be of a type which is resistant to corrosion, such as certain
plastics or stainless steels, or should be protected externally by red oxide primer, undercoat and two top coats of
paint suitable for exterior use in the prevailing atmosphere of the risk.
The use of dissimilar metals should be avoided, and an inert insulating means should be used to limit electrolytic
action.
Colour Coding of Pipework
The pipes should be colour coded in accordance with relevant Standard.
Flushing Of Foam System
Provision should be made in the design to permit the flushing with clean water after the use of any lines which are
normally empty but which have contained foam concentrate, premix solution or made foam.
Water supply mains, both underground and above ground, should be flushed thoroughly at the maximum
practicable rate of flow, before connection is made to system piping, in order to remove foreign materials which
may have entered during installation.

10. The minimum rate of flow for flushing should be not less than the water demand rate of the system, as determined
by the system design and the available water supply. The flow should be continued for a sufficient time to ensure
thorough cleaning. Flushing water should be disposed of outside the system. All foam system piping should be
flushed after installation, using its normal water supply with foam-forming materials shut off, unless the hazard
cannot be subjected to water flow. Where flushing cannot be accomplished, pipe interiors should be carefully
examined for cleanliness during installation.
Pipework scale traps should be provided in the line upstream of foam making equipment. Strainers should be
inspected and cleaned after each use.
Tanks and pipes which are normally filled with liquid should be protected against freezing where appropriate.
OPERATION OF FOAM SYSTEM:
Method
Foam system should be operated manually or automatically, dependent upon the type and location of the risk. In
general, the choice will be governed by the likely rate of fire development, the potential spread to other risks, and
the likely life hazard.
Operating Instructions and Training
The operating instructions for any system, whether manual or automatic, should be located at the control
equipment itself, and also at the plant of fire control centre. All persons who are authorized to operate the system
should be thoroughly trained in its function and method of operation at least once in a month.
Manually-Operated Systems
Controls for these systems should be located in an accessible place sufficiently removed from the hazard zone to
permit them to be safely operated in emergency, yet close enough to ensure that the operator knows the fire-
ground conditions. The location and purposes of the controls should be plainly indicated, and should be related to
the operating instructions.
All operating devices whether manual or automatic should be suitable for the service conditions they will
encounter. They should not be readily rendered inoperative, nor be susceptible to inadvertent operation by
environmental factors such as high or low temperature, atmospheric pollution, humidity, or marine environments.
Automatically-Operated Systems of foam system
Automatic systems should be operated by a detection system which shall give a local alarm as well as an alarm at
the plant or fire control centre.
They should incorporate a manual operating device capable of overriding the automatic control (but not the alarm
signal) if required. The manual override should be relayed to the plant or fire control centre.
Where foam is used for total flooding of an area in which personnel are normally present, the system should be
locked-off from automatic operation unless a suitable delay period is arranged between alarm and system
operation, so that personnel may evacuate the effected area before foam is discharged.
All operating devices whether manual or automatic should be suitable for the service conditions they will
encounter. They should not be readily rendered inoperative, nor be susceptible to inadvertent operation, by
environmental factors such as high or low temperature, atmospheric pollution, humidity, or marine environments.

11. Requirements and Recommendations for Fire Detectors, Alarms and Controls of foam system
a. Detection and alarm equipment may be electrical, pneumatic, hydraulic or mechanical like link, line type.
b. Other than link/line systems, automatic detection and control equipment should be designed to give a
positive warning of any fault or abnormality which may render the system inoperative like loss of power.
c. Automatic detection and control equipment should comply with relevant Standards
d. Automatic detection equipment should provide a local alarm at the control point of each automatic system,
as well as at the plant or central control point.
COMMISSIONING AND PERFORMANCE TESTS OF FOAM
SYSTEM
General
The completed system should be inspected and tested to determine that it is properly installed, and that it will
function as designed. A commissioning test programme should be submitted by the installer.
Inspection
A visual inspection should be conducted to ensure that the system has been installed correctly. Inspection should
include conformity with design drawings and specifications, continuity of pipework, checking, removal of
temporary blinds, accessibility of valves, control and gauges, and proper installation of foam-makers, vapour
seals, and proportioning devices. All equipments should be checked for correct identification and operating
instructions.
Pressure Tests
All pipework, except that handling expanded foam for other than base injection application, should be subjected
to a hydrostatic pressure test at 14 bar or 1·5 times the maximum pressure anticipated, whichever is the greater for
a period of 2 hours. All normally dry horizontal pipework should be inspected for drainage.
Component Inspections
All operating devices and equipments should be inspected for proper functioning and a record should be made to
indicate that the required performance will be met.
Discharge Tests
Whenever possible, flow and distribution tests should be conducted to ensure that the hazard is fully protected in
conformity with the design specification, and to determine the running pressure, actual discharge rate,
consumption rate of foam concentrate, man power requirements and other operating characteristics. Wherever
possible the foam discharged should be inspected and preferably tested to ensure that it is satisfactory for the
intended purpose performance.
System Restoration
After completion of the performance tests, the system should be flushed and restored to operational condition.
MONITORS AND FOAM BRANCH PIPE SYSTEMS
General

12. This systems in which the foam is applied through fixed, portable, or mobile or portable foam branch pipes to
provide primary protection for flammable liquid spills, bund areas and storage tank fires.
NOTE—Portable foam, branch pipes are also suitable for extinguishing rim fires in floating roof tanks.
System Design
General
Consideration should be given to the advantages and limitations when selecting one of many variations of this
type of systems
Possible Advantages
a. Foam can be projected under favourable circumstances, over considerable distances and to significant
heights.
b. Portable and mobile monitor systems may be housed out of the weather, are more likely to be kept in a
serviceable condition, will be unaffected by explosion or flame exposure before firefighting commences
and are available for use in all parts of the complex to be protected. They may also be set up in the most
favourable upwind position.
c. Oscillating monitors discharge foam evenly over very large areas, automatically.
d. Fixed monitors may be remotely controlled from considerable distances thus rendering them suitable, for
example, in oil jetty protection and fire tug use.
Possible Limitations
a. Foam discharge may be affected by any wind and fires up draught resulting in discharge outside the
affected area.
b. Tanks having ruptured roofs with only limited access for foam are not easily extinguished by monitor
application from ground level.
c. Uniform foam distribution may not be achieved easily.
d. Fixed automatically-operated monitors applying foam horizontally into a fire area may be obstructed by
equipment positioned temporarily.
e. Portable foam branch pipes are not suitable for the primary protection of storage tanks of over 9 m
diameter and 6 m height. 9
f. Foam monitors are not generally suitable for the primary protection of fixed roof storage tanks of over 20
m diameter.
g. Monitor systems are not generally suitable for floating roof tank rim fires.
h. Where mobile or portable equipment is used the time required to set up the equipment may increase the
fire preburn period and may make extinction more difficult.
Application Rates
Systems should be designed to deliver not less than the minimum foam solution rates
Duration of Discharge
If the system discharges at a rate above the minimum specified then the operating time may be reduced
proportionately, but should not be less than 70 percent specified discharge time.
Supply of Foam Concentrate

13. The minimum quantity of foam concentrate which should be held in immediate readiness is determined by the
following formulae:
Minimum quantity of foam concentrate
The risk requiring the greatest quantity of foam concentrate should be used to determine the amount to be held at
immediate readiness.
Allowance should be made for the quantity of foam concentrate needed to fill the feed lines installed between the
source and the most remote monitor or branch/pipe. Where it is desired to continue the water supply after the
foam concentrate is exhausted, in order to displace the solution or concentrate in the feed lines, no additional
concentrate need be provided.
There should be a reserve supply of foam-producing materials readily available.